What cardiovascular change commonly occurs during anaphylaxis?

During anaphylaxis, the body experiences a severe allergic reaction that typically leads to widespread vasodilation, which refers to the dilation or widening of blood vessels. This vasodilation causes blood vessels to increase in size, allowing for more space within the circulatory system. As a consequence, despite the heart pumping blood, the overall vascular resistance decreases significantly, leading to a drop in blood pressure.

This drop in blood pressure can be quite severe, which is a critical aspect of anaphylaxis that requires immediate medical intervention. The combination of vasodilation and fluid shifting out of the bloodstream can lead to shock, where organs do not receive adequate blood flow. Understanding this physiological response is key in recognizing and managing anaphylaxis effectively.

In contrast, increased heart rate and high blood pressure would typically indicate a compensatory response to maintain perfusion during a crisis, while increased blood volume does not commonly occur during anaphylaxis.